This disclosure relates generally to the field of computer systems, and more particularly to a computer system that includes a hardware local area network (LAN) and a virtual switch.
A LAN is a computer network that connects computers and devices in a limited geographical area, for example, a home, school, computer laboratory or office building. LANs are often privately owned and located within a single building or site. A LAN may connect personal computers of a company to permit them to share resources such as printers and databases, and to exchange information. A LAN may also be connected to other networks, such as a wide area network (WAN), to enable communication between computers on the different networks. An application running on a computer on a LAN is able to communicate over the LAN with applications on other computers on the LAN, and with computers on external networks using a communications protocol such as transmission control protocol/internet protocol (TCP/IP).
Typically, a LAN may comprise several layers of software and hardware, and a tangible communication medium such as copper wires or fiber optic cables. The communications software and hardware may be embodied in a network interface card (NIC). A physical layer of the LAN is responsible for transmitting data bits over a communication medium. A data link layer organizes the data bits into frames, transmits the frames in proper order, recognizes the beginning and end of a frame, and processes acknowledgements. A network layer determines the routing of the frames from source computer to a destination computer. A session layer creates sessions between different computers to allow transfer data. A transport layer accepts data from a session, divides it into packets, passes these packets to the network layer, and verifies that the packets are received at the destination. A presentation layer is responsible for ensuring proper syntax and semantics of the frames which are transmitted. An application layer is responsible for supporting various data transfer protocols. A LAN may connect many different physical computers, or may be implemented within a single computer, or mainframe.
A simulated LAN may be run internally on a computer system or mainframe. A simulated LAN comprises a plurality of virtual machines (VMs) connected by a virtual switch. The VMs of the simulated LAN communicate with the virtual switch via virtual NICs. Each VM appears to the user to as a personal operating system. Many applications may run on each VM in the simulated LAN. Applications running on the different VMs may communicate with each other via the virtual switch, and may also communicate with other computers on an external LAN that is bridged to the virtual switch via an external uplink port of the virtual switch.
A computer system that includes one or more virtual switches may also include an internal hardware LAN. A hardware LAN also includes multiple VMs; however, the VMs of the hardware LAN communicate with the hardware LAN via dedicated physical hardware NICs. A hardware LAN may be implemented in firmware of the computer system. Hardware LAN VMs may be appropriate for users that require enhanced access to the resources of the computer system that may not be available through VMs that communicate with the computer system via a virtual switch and a virtual NIC.